1. Field of the Invention
The present invention relates to off-road vehicles having a rigid frame and multiple wheels.
2. Background of the Invention
Construction equipment comes in a variety of types such as wheel and track. Wheel type construction equipment includes, for example, wheel loaders (or tool carriers), crawlers (or dozers), motor graders, tractor loader backhoes, wheel excavators and agricultural tractors.
This wide diversity of wheeled equipment has a large number of parts and components. For example, each vehicle has a frame or chassis. Some vehicles have only four wheels, while others have six or more wheels. Even the same type of equipment can have a different number of wheels. For example, a wheel loader can be designed for four wheels or for six wheels. The four wheel design has a relatively short frame while the six wheel design has a larger frame. In addition, the size of the wheels or tires on the vehicle may be determined by the frame size limitations.
Even with vehicles having the same number of wheels, one type of vehicle may have a longer wheel base than another. For example, a wheeled excavator may have a longer power train wheel base than does a motor grader.
Consequently, the design and construction of wheeled equipment is difficult, as a frame or chassis must be custom designed for each type and model of vehicle.
The design of a frame for a multi-wheeled vehicle is made more difficult by the drive and steering mechanisms for the wheels. The wheels or tires must be able to rotate both forward and backward (reverse). In addition, in some steering applications, the wheels on one side of the vehicle rotate in an opposite direction than the wheels on the opposite side (for example, skid steering). Furthermore, some wheels must be able to turn for steering purposes, either independently or in conjunction with other wheels.
There is a need to simplify the design and construction of frames for wheeled vehicles.